To provide a core bar for a spike, the spike, a tire, and footwear capable of providing high safety on a frozen road surface without scratching the road surface.

This core bar for the spike is provided with a plurality of wirelike core materials 11 impregnated by a first polymer material having temperature response property and a cover material 12 for wrapping and bundling a plurality of wirelike core materials 11. The temperature response property has such characteristic that the core bar for the spike is hardened at a temperature lower than transition temperature in the vicinity of 0°C and is softened at a temperature higher than the transition temperature. For example, spike effect appears on the frozen road surface having a temperature lower than 0°C and the core bar for the spike is softened on a non-frozen road surface having a temperature higher than 0°C so that the road surface is not scratched.